The invention relates to plastic material articles having openings therein, which may or may not be closed by film, and to a method of making the articles.
There have been various proposals for making such articles by hot forming or moulding of mesh structures. For instance articles such as brassiere cups and fruit bowls have been made in this manner. British Patent Specification No. 1,027,691 and U.S. Pat. No. 3,642,967 describe methods of this general type. The articles so formed are relatively heavy and/or relatively weak, being formed primarily of unorientated plastic material.
As a technique, vacuum forming is well known, and usually a flat piece of imperforate plastic sheet or film is drawn at an elevated temperature by vacuum into a non-planar shape. British Patent Specification No. 607,995 describes a technique of this type. The articles so formed are relatively weak, being formed primarily of unorientated plastic material.
British Patent Specification No. 2,035,191 A describes a new technique for making flat mesh structures by stretching a starting material which has a pattern of holes or depressions therein, forming strong structures with a high degree of orientation. This Specification however does not disclose non-planar articles.